The present invention relates to the synthesis of nanogel core star polymers with improved loading of hydrophobic cargo, and more specifically, to nanogel core star polymers having pendant alkyl functionality for improved cargo loading.
Commercial interest exists in developing biocompatible, well-defined polymer-based particles for the in vivo delivery of exogenous functional medically useful materials (e.g., pharmaceuticals and/or imaging agents). Organic nanoparticle platforms under development for these purposes include liposomes, dendrimers, and micelles. Alternatively, star polymers having a unimolecular, globular, polymer architecture are an increasingly attractive class of organic nanoparticles for biomedical research purposes (e.g., see Bencherif, S. A., et al., Biomacromolecules 2009, 10, 1795-1803; Fukukawa, K.-I., et al., Biomacromolecules 2008, 9, 1329; and Georgiou, T. K., et al., Biomacromolecules 2005, 6, 2990).
While topographically similar to dendrimers, (i.e., having a high local density of polymeric arms, surface functionality and interstitial regions), star polymers lack the synthetic and structural limitations of dendrimers and the dynamic instability of micelles and liposomes. Nanogel star polymers, which have polymer “arms” connected to a cross-linked polymer core, in particular, offer a modular platform in which the nanoparticle size, the number of arms, the nature of the arms, the core, as well as inner functionality of the core and the end (peripheral) functionality of the arms can be selectively modified.
Of specific importance to biomedical applications is the development and characterization of poly(ethylene glycol) (PEG) functionalized star polymers. The high water solubility and low immunogenicity of PEG have made PEG the most recognized polymer composition for promoting increased circulation time and biocompatibility of nanoparticles in vivo. Owing to previous synthetic difficulties, there has been limited work done on PEG-based nanogel-core star polymers as a nanoparticle platform for drug delivery.
Thus, nanogel-core star polymers are desired having PEG-functionalized arms that exhibit high loading efficiencies with respect to hydrophobic therapeutic agents used in medical treatments and cosmetic applications.